The new school year is under way in a whoosh of the predictable: Students are hustling to settlinge into rooms and classes. Staff and faculty are gearing up after summer’s lull. The Cal Bears have high hopes for the football season.

But what about the unpredictable? An emergency could strike campus at any moment — an earthquake, or a fire, or someone with a gun.

It’s not the kind of thing too many people are focused on amid the bustle of a shiny new semester.

But campus security experts say this is the best time to take one simple step to prepare: Sign up for WarnMe.

WarnMe is a computerized emergency notification system. In a crisis, it allows emergency staff to send out text, phone and e-mail messages alerting the campus community and relaying instructions about what to do.

“It’s a really great system, one of the best tools out there,” says Stephen Stoll, Berkeley’s director of emergency preparedness and homeland security. “But you have to sign up for it.”

WarnMe is an opt-in system, so it’s up to students, staff and faculty to enroll; no one is automatically signed up. And people who have already signed up need to make sure their contact information is up-to-date.

Both can be accomplished on the WarnMe website (warnme.berkeley.edu), where details about the system are posted along with links to new or current accounts. All that’s required is a CalNet ID.

New enrollees will be asked to enter their contact information, and list their notification preferences. E-mail first, or text? Cell phone or landline? Seven options are listed.

“The system doesn’t quit until it gets ahold of you,” Stoll explains. If texting is your first choice, but a WarnMe text message doesn’t get a response, the system will try your second choice, and so on, until an acknowledgement is received.”

Berkeley, along with many other campuses around the country, initiated its emergency alert and information system after a student with a gun killed 32 people, and then himself, on the Virginia Tech campus in 2007. At Berkeley, WarnMe augments an existing network of four emergency sirens and a public-address system.

WarnMe allows emergency notifications to be tailored to the crisis at hand. For instance, in a scenario like Virginia Tech’s, Stoll says, it allows the campus community to be notified and instructed about what to do without a general alarm tipping off the person with the gun.

Active messages would begin with “emergency,” “urgent” or “important.” They would include a description of the situation, and a recommendation for action. As a situation develops or changes, the system can deliver follow-up messages with more specifics.

Since the system went live in 2008, it has never been activated in response to a real emergency. Every month, WarnMe is tested by sending messages to a small number of people.

So far, 22,000-plus people are on board, according to Stoll. He wants everybody on campus signed up.

“WarnMe is the quickest and most effective way of notifying a large group of people about an immediate threat to their safety and health,” he says.

WarnMe is just part of the campus’s communications network in case of an emergency, natural disaster or crisis. Information also will be posted on the campus homepage, (www.berkeley.edu) and on the off-site emergency website. It will also be recorded on the off-site emergency telephone number, 1-800-705-9998, and broadcast on the campus radio station, KALX 90.7 FM.

The campus siren alert is tested on the first Wednesday of every month. At all other times, the siren means people should shelter in place and go to the campus website or the emergency website, call the 800 number or tune in to KALX for information and instructions.